When assembling a pipe string, such as a drill string, a completion string, or other well related equipment, care needs to be taken when carrying out the steps of joining a tubular element such as, for example, a pipe element, to the existing pipe string. Because the pipe elements to be joined with the drill string may have a considerable weight, special care needs to be taken when transferring the weight of the pipe element to the drill string so that the end joints, such as, for example, threads making up a screw joint, are not damaged when establishing contact between the pipe element and the existing drill string.
This problem is well known within the technical field. Several attempts have been made to provide solutions to set off the weight of the pipe element to be joined with the pipe string in order to save the end joints when connecting the pipe element and the pipe string.
The following documents disclose relevant prior art solutions:
US 2013/0146304 describes an arrangement for compensating the weight of a tubular element. A tubular compensator is provided to carry the tubular element to be connected with the completion string. The tubular compensator comprises roller assemblies. The roller assemblies are vertically adjusted by pressure controlled pistons in accordance with the force applied by the tubular element to counterbalance the weight of the tubular elements to save the threads in the connection between the tubular element and the completion string. The tubular compensator is hoisted by the travelling block for positioning the tubular element before coupling with the tubular string.
EP 142477 describes a telescoping arm arrangement to position a pipe element onto a drill string. A grab head is articulated to the telescoping arm to hold the pipe element, and a cylinder is provided to rotate one of the telescoping arm arrangements. The cylinder may also be used as weight compensating means for a pipe element to be connected to the drill string.
Because most prior art solutions are complex assemblies which occupy a relatively large space, a need has developed within the field for providing a simple solution which is easy to operate and maintain, and which occupies a relatively small space.